The bone spindle
(Book)

Series information from Goodreads.

Fi is a bookish treasure hunter with a knack for ruins and riddles, who definitely doesn't believe in true love. Shane is a tough-as-dirt girl warrior from the north who likes cracking skulls, pretty girls, and doing things her own way. Briar Rose is a prince under a sleeping curse, who's been waiting a hundred years for the kiss that will wake him. Cursed princes are nothing but ancient history to Fi--until she pricks her finger on a bone spindle while exploring a long-lost ruin. Now she's stuck with the spirit of Briar Rose until she and Shane can break the century-old curse on his kingdom. Dark magic, Witch Hunters, and bad exes all stand in her way--not to mention a mysterious witch who might wind up stealing Shane's heart, along with whatever else she's after. But nothing scares Fi more than the possibility of falling in love with Briar Rose.